Talk:tiankeng

Taken from article: in IFL SCIENCE by author Charlie Haigh that I copy pasted.

To be a tiankeng, the sinkhole must be at least 100 meters (328 feet) deep and wide, with a river flowing through the bottom. All tiankeng are comprised of carbonate rock, with the exception of two Venezuelan structures that consist of sandstone. They’re formed through a karst process when their composition is carbonate rock, and a suffusion process when made of sandstone.

The conditions required to form a tiankeng are very specific, making their formation rare. The rock must be above sea level, and be thick with no layers of impurities. Heavy rain is also required to form these structures, which in turn helps form their underground rivers.

Although the term refers to any sinkhole within these criteria, of the 75 identified, 50 of the largest are found in China, hence the Chinese term becoming the commonplace name for such structures.